@sbflyfan Defying Gravity ends with a black out, so the whole theatre goes dark. The audience wouldn't normally notice the pit lights (and video screens) but they would if they were the only lights in the auditorium, and would ruin the effect of the black out.
The lighting designer would ask for it, but could be suggested by any creative (director, set designer etc). Bit difficult to do, as the video feeds are normally sorted by the sound department (stupid tradition but that is the way it s), so requires cross department interfacing to do.